CONTENTS. Xlll 



PART III APPLIED MICROBIOLOGY. 

 DIVISION I. MICROBIOLOGY OF AIR (Buchanan). 



CHAPTER I. THE MICROORGANISMS OF THE AIR AND THEIR DISTRIBUTION 185 



Microorganisms present in the air. Occurrence in the air. How microorganisms 

 enter the air. Conditions for subsidence of bacteria. Determination of the number 

 of bacteria in the air. Number of bacteria in the air. Species of organisms in the air. 



CHAPTER II. MICROBIAL AIR INFLUENCE IN FERMENTATION, DISEASES, ETC 19 



Air as a carrier of contagion. Organisms of the air and fermentation. Freeing air 

 from bacteria. 



DIVISION II. MICROBIOLOGY or WATER AND SEWAGE. 



CHAPTER I. MICROORGANISMS IN WATER (Harrison) 192 



Classes of bacteria found in water, Natural water bacteria, soil bacteria and surface 

 washings, intestinal bacteria usually of sewage origin. The number of bacteria in rain , 

 snow, hail, etc., and in water from wells, up-land, surface waters, rivers, and lakes. 

 Causes affecting the increase and decrease of the number of bacteria in water, Tem- 

 perature, light, food supply, oxidation, vegetation and protozoa, dilution, sedimenta- 

 tion, other causes. Interpretation of the bacteriological analysis of water, Quantita- 

 tive standards, qualitative standards. Sedimentation, filtration and purification of 

 water, Sedimentation and filtration, coagulation basins and filtration, porous filters, 

 purification by ozone, purification by heat, purification by chemicals. Location 

 and construction of wells. 



CHAPTER II. MICROBIOLOGY OF SEWAGE (Phelps) 212 



Bacterial flora of sewage. Types of sewage bacteria, Putrefactive and anaerobic 

 bacteria (the liquefaction of protein, the fermentation of cellulose, the saponification 

 of fats, the fermentation of urea, the reduction of sulphates and nitrates), oxidizing 

 bacteria (the production of nitrates and nitrites, other oxidizing reactions) , patho- 

 genic bacteria (prevalence and longevity, life in septic tanks and filters). The culti- 

 vation of sewage bacteria, Filters, anaerobic tanks. The destruction of sewage 

 bacteria, By biological processes, by chemical processes. 



DIVISION III. MICROBIOLOGY OF SOIL (Lipman). 



CHAPTER I. MICROORGANISMS OF THE SOIL AS A FACTOR IN SOIL FERTILITY 226 



Introduction. The soil as a culture medium; Moisture relations, The amount 

 and distribution of rain fall, range of soil moisture, effect of drouth and exces- 

 sive moisture. Aeration, Mechanical composition of soils, aerobic and anaerobic 

 activities, rate of oxidation of carbon, hydrogen and nitrogen, the mineralization 

 of organic matter. Temperature, Influence of climate and season, early and late 

 soils, production and assimilation of plant food. Reaction, Range of soil acidity, 

 causes of soil acidity, effect of reaction on number and species.- Food supply, Or- 

 ganic matter, the mineral portion of the soil. Biological factors, Molds, algae, proto- 

 zoa, higher plants, bacteria, (numbers and distribution, bacteria in productive and 

 unproductive soils, distribution at different depths, morphological and physiological 

 groups). Methods of study, Quantitative relations, qualitative reaction, transforma- 

 tion reactions, rate of oxidation of carbon, rate of oxidation of nitrogen, addition of 

 nitrogen, reactions concerning calcium, magnesium, sulphur, phosphorus. 



CHAPTER II. DECOMPOSITION OF ORGANIC MATTER IN THE SOIL 246 



Carbohydrates, Origin, decomposition of cellulose, the production of methane and 

 hydrogen, oxidation of methane, hydrogen, and carbon monoxide, the cleavage and 

 fermentation of sugars, starches, and gums. Fats and waxes, Origin and decomposi- 



